1. Field of the Invention
The present invention relates to a rotary engine, and, more particularly, to a rotary engine which can improve sealing performance between an inner circumferential contact wall of a cylinder chamber and a seal face of a rotor that comes into contact with the inner circumferential contact wall and can minimize leakage of gas mixture during a compression stroke to reduce exhaust gas, thereby achieving an enhancement in engine output and an enhancement in fuel efficiency.
2. Description of the Related Art
A rotary engine is designed to obtain rotational power by performing four strokes, for example, intake, compression, expansion, and exhaust strokes, as in a piston reciprocating engine. However, the rotary engine clearly differs from the piston reciprocating engine in the structure of a mover which is used to induce the four strokes. In the piston reciprocating engine, the four strokes are induced as the reciprocating motion of a piston is converted into the rotating motion of a crankshaft.
That is, the piston reciprocating engine obtains rotational power as a piston, which is coupled to a crankshaft, linearly reciprocates in a cylinder to implement four strokes. On the other hand, the rotary engine obtains rotational power as a rotor, which serves as a piston, rotates in a cylinder to implement four strokes. Another great difference between the piston reciprocating engine and the rotary engine is that the rotational power obtained by the rotor is directly transmitted to an output shaft.
Considering the general structure of the rotary engine, an eccentric shaft is coupled to the center of a triangular rotor to lead the position of the rotor. Thereby, when the rotor rotates, respective vertexes of the triangular rotor describe a specific curve, which determines the shape of a cylinder chamber. Normally, the cylinder chamber has an elliptical or peanut shape.
The triangular rotor divides the peanut shaped cylinder chamber into three cylinder chambers, so that the three cylinder chambers implement four strokes independently. On the other words, three expansion strokes occur per every rotation of the rotor, generating rotational power. The rotary engine has an advantage of temporarily raising angular velocity of the rotor because it has no inverted inertia as seen in the piston reciprocating engine.
However, the rotary engine, having the above described configuration, has a problem in that a contact angle between the inner circumferential contact wall of the cylinder chamber and a seal face of the rotor for the maintenance of air-tightness greatly varies in a range of ±20°. Also, it is impossible to maintain perfect air-tightness because the inner wall of the cylinder chamber shows uneven wear differently from the piston reciprocating engine, and, in particular, it is difficult to maintain air-tightness during a compression stroke. This is a representative disadvantage occurred in most rotary engines.
Due to the imperfect air-tightness between the inner circumferential contact wall of the cylinder chamber and the seal face of the rotor, the conventional rotary engine suffers from degradation in engine performance, and causes gas mixture to leak during the compression stroke to thereby be exhausted in uncombusted state. This disadvantageously results in waste of fuel and air pollution.
Thus, the maintenance of perfect air-tightness is the most urgent subject to be solved for the development and performance enhancement of the rotary engine.